The invention relates to a device for filtering contaminants, such as particulates and vapor phase contaminants, from a confined environment such as electronic or optical devices susceptible to contamination (e.g. computer disk drives) by improving performance and possibly incorporating multiple filtration functions into a unitary filter. Filtration functions include a passive adsorbent assembly and can include a combination of inlet, or breather filter and adsorbent filter. Moreover, recirculation filter, diffusion tube, and outside mount functions can be added to the filter depending on desired functionality within the enclosure.